Internet Engineering Task Force (IETF) L. Avramov
Request for Comments: 8238 Google
Category: Informational J. Rapp
ISSN: 2070-1721 VMware
August 2017
Internet Engineering Task Force (IETF) L. Avramov
Request for Comments: 8238 Google
Category: Informational J. Rapp
ISSN: 2070-1721 VMware
August 2017
Data Center Benchmarking Terminology
数据中心基准术语
Abstract
摘要
The purposes of this informational document are to establish definitions and describe measurement techniques for data center benchmarking, as well as to introduce new terminology applicable to performance evaluations of data center network equipment. This document establishes the important concepts for benchmarking network switches and routers in the data center and is a prerequisite for the test methodology document (RFC 8239). Many of these terms and methods may be applicable to network equipment beyond the scope of this document as the technologies originally applied in the data center are deployed elsewhere.
本信息性文档旨在为数据中心基准测试建立定义和描述测量技术，并介绍适用于数据中心网络设备性能评估的新术语。本文件确立了数据中心网络交换机和路由器基准测试的重要概念，是测试方法文件（RFC 8239）的先决条件。其中许多术语和方法可能适用于本文件范围以外的网络设备，因为最初应用于数据中心的技术部署在其他地方。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for informational purposes.
本文件不是互联网标准跟踪规范；它是为了提供信息而发布的。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 7841第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc8238.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc8238.
Copyright Notice
版权公告
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2017 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
1.1. Requirements Language ......................................5
1.2. Definition Format ..........................................5
2. Latency .........................................................5
2.1. Definition .................................................5
2.2. Discussion .................................................7
2.3. Measurement Units ..........................................7
3. Jitter ..........................................................8
3.1. Definition .................................................8
3.2. Discussion .................................................8
3.3. Measurement Units ..........................................8
4. Calibration of the Physical Layer ...............................9
4.1. Definition .................................................9
4.2. Discussion .................................................9
4.3. Measurement Units ..........................................9
5. Line Rate ......................................................10
5.1. Definition ................................................10
5.2. Discussion ................................................10
5.3. Measurement Units .........................................11
6. Buffering ......................................................12
6.1. Buffer ....................................................12
6.1.1. Definition .........................................12
6.1.2. Discussion .........................................14
6.1.3. Measurement Units ..................................14
6.2. Incast ....................................................15
6.2.1. Definition .........................................15
6.2.2. Discussion .........................................15
6.2.3. Measurement Units ..................................16
7. Application Throughput: Data Center Goodput ....................16
7.1. Definition ................................................16
7.2. Discussion ................................................16
7.3. Measurement Units .........................................16
8. Security Considerations ........................................17
9. IANA Considerations ............................................18
10. References ....................................................18
10.1. Normative References .....................................18
10.2. Informative References ...................................19
Acknowledgments ...................................................20
Authors' Addresses ................................................20
1. Introduction ....................................................4
1.1. Requirements Language ......................................5
1.2. Definition Format ..........................................5
2. Latency .........................................................5
2.1. Definition .................................................5
2.2. Discussion .................................................7
2.3. Measurement Units ..........................................7
3. Jitter ..........................................................8
3.1. Definition .................................................8
3.2. Discussion .................................................8
3.3. Measurement Units ..........................................8
4. Calibration of the Physical Layer ...............................9
4.1. Definition .................................................9
4.2. Discussion .................................................9
4.3. Measurement Units ..........................................9
5. Line Rate ......................................................10
5.1. Definition ................................................10
5.2. Discussion ................................................10
5.3. Measurement Units .........................................11
6. Buffering ......................................................12
6.1. Buffer ....................................................12
6.1.1. Definition .........................................12
6.1.2. Discussion .........................................14
6.1.3. Measurement Units ..................................14
6.2. Incast ....................................................15
6.2.1. Definition .........................................15
6.2.2. Discussion .........................................15
6.2.3. Measurement Units ..................................16
7. Application Throughput: Data Center Goodput ....................16
7.1. Definition ................................................16
7.2. Discussion ................................................16
7.3. Measurement Units .........................................16
8. Security Considerations ........................................17
9. IANA Considerations ............................................18
10. References ....................................................18
10.1. Normative References .....................................18
10.2. Informative References ...................................19
Acknowledgments ...................................................20
Authors' Addresses ................................................20
Traffic patterns in the data center are not uniform and are constantly changing. They are dictated by the nature and variety of applications utilized in the data center. They can be largely east-west traffic flows (server to server inside the data center) in one data center and north-south (from the outside of the data center to the server) in another, while some may combine both. Traffic patterns can be bursty in nature and contain many-to-one, many-to-many, or one-to-many flows. Each flow may also be small and latency sensitive or large and throughput sensitive while containing a mix of UDP and TCP traffic. All of these may coexist in a single cluster and flow through a single network device simultaneously. Benchmarking tests for network devices have long used [RFC1242], [RFC2432], [RFC2544], [RFC2889], and [RFC3918]. These benchmarks have largely been focused around various latency attributes and max throughput of the Device Under Test (DUT) being benchmarked. These standards are good at measuring theoretical max throughput, forwarding rates, and latency under testing conditions, but they do not represent real traffic patterns that may affect these networking devices. The data center networking devices covered are switches and routers.
数据中心的流量模式并不统一，而且不断变化。它们由数据中心中使用的应用程序的性质和种类决定。它们可以是一个数据中心中的东西向流量（数据中心内部的服务器到服务器），也可以是另一个数据中心中的南北向流量（从数据中心外部到服务器），而有些流量可能两者兼而有之。流量模式本质上可能是突发性的，包含多对一、多对多或一对多流量。当包含UDP和TCP流量的混合时，每个流也可能是小的、对延迟敏感的，或者是大的、对吞吐量敏感的。所有这些可能共存于单个集群中，并同时流经单个网络设备。网络设备的基准测试长期使用[RFC1242]、[RFC2432]、[RFC2544]、[RFC2889]和[RFC3918]。这些基准测试主要关注各种延迟属性和被测试设备（DUT）的最大吞吐量。这些标准擅长测量测试条件下的理论最大吞吐量、转发速率和延迟，但它们并不代表可能影响这些网络设备的真实流量模式。数据中心网络设备包括交换机和路由器。
Currently, typical data center networking devices are characterized by:
目前，典型的数据中心网络设备具有以下特点：
- High port density (48 ports or more).
- 高端口密度（48个或更多端口）。
- High speed (currently, up to 100 GB/s per port).
- 高速（目前，每个端口高达100 GB/s）。
- High throughput (line rate on all ports for Layer 2 and/or Layer 3).
- 高吞吐量（第2层和/或第3层的所有端口上的线路速率）。
- Low latency (in the microsecond or nanosecond range).
- 低延迟（在微秒或纳秒范围内）。
- Low amount of buffer (in the MB range per networking device).
- 缓冲区容量低（每个网络设备的MB范围内）。
- Layer 2 and Layer 3 forwarding capability (Layer 3 not mandatory).
- 第2层和第3层转发能力（第3层不是强制性的）。
This document defines a set of definitions, metrics, and new terminology, including congestion scenarios and switch buffer analysis, and redefines basic definitions in order to represent a wide mix of traffic conditions. The test methodologies are defined in [RFC8239].
本文档定义了一组定义、指标和新术语，包括拥塞场景和交换机缓冲区分析，并重新定义了基本定义，以表示各种流量条件。[RFC8239]中定义了测试方法。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“建议”、“不建议”、“可”和“可选”在所有大写字母出现时（如图所示）应按照BCP 14[RFC2119][RFC8174]所述进行解释。
- Term to be defined (e.g., "latency").
- 待定义的术语（例如，“延迟”）。
- Definition: The specific definition for the term.
- 定义：该术语的具体定义。
- Discussion: A brief discussion about the term, its application, and any restrictions on measurement procedures.
- 讨论：简要讨论该术语、其应用以及对测量程序的任何限制。
- Measurement Units: Methodology for measurements and units used to report measurements of the term in question, if applicable.
- 测量单位：测量方法和用于报告相关术语测量的单位（如适用）。
Latency is the amount of time it takes a frame to transit the DUT. Latency is measured in units of time (seconds, milliseconds, microseconds, and so on). The purpose of measuring latency is to understand the impact of adding a device in the communication path.
延迟是帧传输DUT所需的时间量。延迟以时间单位（秒、毫秒、微秒等）测量。测量延迟的目的是了解在通信路径中添加设备的影响。
The latency interval can be assessed between different combinations of events, regardless of the type of switching device (bit forwarding, aka cut-through; or a store-and-forward device). [RFC1242] defined latency differently for each of these types of devices.
可以在不同的事件组合之间评估延迟间隔，而不考虑交换设备的类型（位转发，也称为直通；或存储转发设备）。[RFC1242]为每种类型的设备定义了不同的延迟。
Traditionally, the latency measurement definitions are:
传统上，延迟测量定义为：
- FILO (First In Last Out):
- FILO（先进先出）：
The time interval starting when the end of the first bit of the input frame reaches the input port and ending when the last bit of the output frame is seen on the output port.
从输入帧的第一位的末尾到达输入端口时开始，到输出端口上看到输出帧的最后一位时结束的时间间隔。
- FIFO (First In First Out):
- 先进先出（先进先出）：
The time interval starting when the end of the first bit of the input frame reaches the input port and ending when the start of the first bit of the output frame is seen on the output port. Latency (as defined in [RFC1242]) for bit-forwarding devices uses these events.
从输入帧的第一位的末尾到达输入端口时开始，到输出端口上看到输出帧的第一位的开头时结束的时间间隔。位转发设备的延迟（定义见[RFC1242]）使用这些事件。
- LILO (Last In Last Out):
- LILO（后进后出）：
The time interval starting when the last bit of the input frame reaches the input port and the last bit of the output frame is seen on the output port.
从输入帧的最后一位到达输入端口和输出帧的最后一位出现在输出端口时开始的时间间隔。
- LIFO (Last In First Out):
- 后进先出（后进先出）：
The time interval starting when the last bit of the input frame reaches the input port and ending when the first bit of the output frame is seen on the output port. Latency (as defined in [RFC1242]) for store-and-forward devices uses these events.
从输入帧的最后一位到达输入端口时开始，到输出端口上看到输出帧的第一位时结束的时间间隔。存储和转发设备的延迟（定义见[RFC1242]）使用这些事件。
Another possible way to summarize the four definitions above is to refer to the bit positions as they normally occur: input to output.
总结上述四种定义的另一种可能方式是引用通常出现的位位置：输入到输出。
- FILO is FL (First bit Last bit).
- FILO是FL（第一位最后一位）。
- FIFO is FF (First bit First bit).
- FIFO是FF（第一位第一位）。
- LILO is LL (Last bit Last bit).
- LILO是LL（最后一位最后一位）。
- LIFO is LF (Last bit First bit).
- 后进先出是LF（最后一位第一位）。
This definition, as explained in this section in the context of data center switch benchmarking, is in lieu of the previous definition of "latency" as provided in RFC 1242, Section 3.8 and quoted here:
如本节在数据中心交换机基准测试中所述，此定义取代RFC 1242第3.8节中提供的先前“延迟”定义，并在此处引用：
For store and forward devices: The time interval starting when the last bit of the input frame reaches the input port and ending when the first bit of the output frame is seen on the output port.
对于存储转发设备：从输入帧的最后一位到达输入端口开始，到输出端口上看到输出帧的第一位结束的时间间隔。
For bit forwarding devices: The time interval starting when the end of the first bit of the input frame reaches the input port and ending when the start of the first bit of the output frame is seen on the output port.
对于位转发设备：从输入帧的第一位的末尾到达输入端口开始，到输出端口上看到输出帧的第一位的开头结束的时间间隔。
To accommodate both types of network devices and hybrids of the two types that have emerged, switch latency measurements made according to this document MUST be measured with the FILO events. FILO will include the latency of the switch and the latency of the frame as well as the serialization delay. It is a picture of the "whole" latency going through the DUT. For applications that are latency sensitive and can function with initial bytes of the frame, FIFO (or, for bit-forwarding devices, latency per RFC 1242) MAY be used. In all cases, the event combinations used in latency measurements MUST be reported.
为了适应两种类型的网络设备以及两种类型的混合，根据本文档进行的交换机延迟测量必须使用FILO事件进行测量。FILO将包括交换机的延迟、帧的延迟以及序列化延迟。这是通过DUT的“整个”延迟的图片。对于对延迟敏感并且可以使用帧的初始字节的应用程序，可以使用FIFO（或者，对于位转发设备，每个RFC 1242的延迟）。在所有情况下，必须报告延迟测量中使用的事件组合。
As mentioned in Section 2.1, FILO is the most important measuring definition.
如第2.1节所述，FILO是最重要的测量定义。
Not all DUTs are exclusively cut-through or store-and-forward. Data center DUTs are frequently store-and-forward for smaller packet sizes and then change to cut-through behavior at specific larger packet sizes. The value of the packet size at which the behavior changes MAY be configurable, depending on the DUT manufacturer. FILO covers both scenarios: store-and-forward and cut-through. The threshold for the change in behavior does not matter for benchmarking, since FILO covers both possible scenarios.
并非所有DUT都是专用直通或存储转发的。数据中心DUT经常存储和转发较小的数据包大小，然后更改为特定较大数据包大小的直通行为。根据DUT制造商的不同，可配置行为改变时的数据包大小值。FILO涵盖了两种场景：存储、转发和直通。行为变化的阈值对于基准测试并不重要，因为FILO涵盖了两种可能的场景。
The LIFO mechanism can be used with store-and-forward switches but not with cut-through switches, as it will provide negative latency values for larger packet sizes because LIFO removes the serialization delay. Therefore, this mechanism MUST NOT be used when comparing the latencies of two different DUTs.
后进先出机制可用于存储和转发交换机，但不能用于直通交换机，因为后进先出机制消除了序列化延迟，因此它将为较大的数据包大小提供负延迟值。因此，在比较两个不同DUT的延迟时，不得使用此机制。
The measuring methods to use for benchmarking purposes are as follows:
用于基准测试的测量方法如下：
1) FILO MUST be used as a measuring method, as this will include the latency of the packet; today, the application commonly needs to read the whole packet to process the information and take an action.
1) FILO必须用作测量方法，因为这将包括数据包的延迟；如今，应用程序通常需要读取整个数据包来处理信息并采取行动。
2) FIFO MAY be used for certain applications able to process the data as the first bits arrive -- for example, with a Field-Programmable Gate Array (FPGA).
2) FIFO可用于某些能够在第一位到达时处理数据的应用，例如，使用现场可编程门阵列（FPGA）。
3) LIFO MUST NOT be used because, unlike all the other methods, it subtracts the latency of the packet.
3) 不能使用后进先出法，因为与所有其他方法不同，后进先出法减去数据包的延迟。
In the context of the data center, jitter is synonymous with the common term "delay variation". It is derived from multiple measurements of one-way delay, as described in RFC 3393. The mandatory definition of "delay variation" is the Packet Delay Variation (PDV) as defined in Section 4.2 of [RFC5481]. When considering a stream of packets, the delays of all packets are subtracted from the minimum delay over all packets in the stream. This facilitates the assessment of the range of delay variation (Max - Min) or a high percentile of PDV (99th percentile, for robustness against outliers).
在数据中心的上下文中，抖动与常用术语“延迟变化”同义。如RFC 3393所述，它源自单向延迟的多次测量。“延迟变化”的强制性定义是[RFC5481]第4.2节中定义的数据包延迟变化（PDV）。当考虑数据包流时，从流中所有数据包的最小延迟中减去所有数据包的延迟。这有助于评估延迟变化范围（最大-最小值）或PDV的高百分位（第99百分位，针对异常值的鲁棒性）。
When First-bit to Last-bit timestamps are used for delay measurement, then delay variation MUST be measured using packets or frames of the same size, since the definition of latency includes the serialization time for each packet. Otherwise, if using First-bit to First-bit, the size restriction does not apply.
当第一位到最后一位的时间戳用于延迟测量时，必须使用相同大小的数据包或帧来测量延迟变化，因为延迟的定义包括每个数据包的序列化时间。否则，如果使用第一位到第一位，则大小限制不适用。
In addition to a PDV range and/or a high percentile of PDV, Inter-Packet Delay Variation (IPDV) as defined in Section 4.1 of [RFC5481] (differences between two consecutive packets) MAY be used for the purpose of determining how packet spacing has changed during transfer -- for example, to see if a packet stream has become closely spaced or "bursty". However, the absolute value of IPDV SHOULD NOT be used, as this "collapses" the "bursty" and "dispersed" sides of the IPDV distribution together.
除了PDV范围和/或PDV的高百分位数外，[RFC5481]第4.1节（两个连续数据包之间的差异）中定义的数据包间延迟变化（IPDV）可用于确定数据包间隔在传输过程中如何变化，例如，查看数据包流是否变得紧密间隔或“突发性”。但是，不应使用IPDV的绝对值，因为这将IPDV分布的“突发性”和“分散性”边“折叠”在一起。
The measurement of delay variation is expressed in units of seconds. A PDV histogram MAY be provided for the population of packets measured.
延迟变化的测量以秒为单位。可以为测量的分组的总体提供PDV直方图。
Calibration of the physical layer consists of defining and measuring the latency of the physical devices used to perform tests on the DUT.
物理层的校准包括定义和测量用于在DUT上执行测试的物理设备的延迟。
It includes the list of all physical-layer components used, as specified here:
它包括使用的所有物理层组件的列表，如下所述：
- Type of device used to generate traffic / measure traffic.
- 用于生成流量/测量流量的设备类型。
- Type of line cards used on the traffic generator.
- 流量生成器上使用的线路卡类型。
- Type of transceivers on the traffic generator.
- 流量生成器上的收发器类型。
- Type of transceivers on the DUT.
- DUT上的收发器类型。
- Type of cables.
- 电缆类型。
- Length of cables.
- 电缆长度。
- Software name and version of the traffic generator and DUT.
- 流量生成器和DUT的软件名称和版本。
- A list of enabled features on the DUT MAY be provided and is recommended (especially in the case of control-plane protocols, such as the Link Layer Discovery Protocol and Spanning Tree). A comprehensive configuration file MAY be provided to this effect.
- 可以提供并推荐DUT上的已启用特征的列表（特别是在控制平面协议的情况下，例如链路层发现协议和生成树）。为此，可以提供一个全面的配置文件。
Calibration of the physical layer contributes to end-to-end latency and should be taken into account when evaluating the DUT. Small variations in the physical components of the test may impact the latency being measured; therefore, they MUST be described when presenting results.
物理层的校准会导致端到端延迟，在评估DUT时应予以考虑。测试物理组件的微小变化可能会影响测量的延迟；因此，在呈现结果时必须对其进行描述。
It is RECOMMENDED that all cables used for testing (1) be of the same type and length and (2) come from the same vendor whenever possible. It is a MUST to document the cable specifications listed in Section 4.1, along with the test results. The test report MUST specify whether or not the cable latency has been subtracted from the test measurements. The accuracy of the traffic-generator measurements MUST be provided (for current test equipment, this is usually a value within a range of 20 ns).
建议用于测试的所有电缆（1）应具有相同的类型和长度，（2）尽可能来自同一供应商。必须记录第4.1节中列出的电缆规范以及测试结果。测试报告必须说明是否已从测试测量值中减去电缆延迟。必须提供流量发生器测量的准确度（对于当前测试设备，该值通常在20 ns范围内）。
The transmit timing, or maximum transmitted data rate, is controlled by the "transmit clock" in the DUT. The receive timing (maximum ingress data rate) is derived from the transmit clock of the connected interface.
传输定时或最大传输数据速率由DUT中的“传输时钟”控制。接收定时（最大进入数据速率）源自所连接接口的发送时钟。
The line rate or physical-layer frame rate is the maximum capacity to send frames of a specific size at the transmit clock frequency of the DUT.
线速率或物理层帧速率是在DUT的发射时钟频率下发送特定大小的帧的最大容量。
The term "nominal value of line rate" defines the maximum speed capability for the given port -- for example (expressed as Gigabit Ethernet), 1 GE, 10 GE, 40 GE, 100 GE.
术语“线路速率的标称值”定义了给定端口的最大速度容量——例如（表示为千兆以太网）、1GE、10GE、40GE、100GE。
The frequency ("clock rate") of the transmit clock in any two connected interfaces will never be precisely the same; therefore, a tolerance is needed. This will be expressed by a Parts Per Million (PPM) value. The IEEE standards allow a specific +/- variance in the transmit clock rate, and Ethernet is designed to allow for small, normal variations between the two clock rates. This results in a tolerance of the line-rate value when traffic is generated from test equipment to a DUT.
任何两个连接接口中传输时钟的频率（“时钟频率”）永远不会完全相同；因此，需要一个公差。这将用百万分之一（PPM）值表示。IEEE标准允许传输时钟速率存在特定的+/-变化，以太网的设计允许两个时钟速率之间存在微小的正常变化。当从测试设备到DUT产生通信量时，这导致线路速率值的公差。
Line rate SHOULD be measured in frames per second (FPS).
测线速率应以每秒帧数（FPS）为单位进行测量。
For a transmit clock source, most Ethernet switches use "clock modules" (also called "oscillator modules") that are sealed, internally temperature-compensated, and very accurate. The output frequency of these modules is not adjustable because it is not necessary. Many test sets, however, offer a software-controlled adjustment of the transmit clock rate. These adjustments SHOULD be used to "compensate" the test equipment in order to not send more than the line rate of the DUT.
对于传输时钟源，大多数以太网交换机使用密封、内部温度补偿且非常精确的“时钟模块”（也称为“振荡器模块”）。这些模块的输出频率不可调，因为不需要。然而，许多测试集提供软件控制的传输时钟速率调整。这些调整应用于“补偿”测试设备，以不发送超过DUT线路速率的信号。
To allow for the minor variations typically found in the clock rate of commercially available clock modules and other crystal-based oscillators, Ethernet standards specify the maximum transmit clock-rate variation to be not more than +/- 100 PPM from a calculated center frequency. Therefore, a DUT must be able to accept frames at a rate within +/- 100 PPM to comply with the standards.
为了考虑商用时钟模块和其他基于晶体的振荡器的时钟速率中通常存在的微小变化，以太网标准规定最大传输时钟速率变化与计算的中心频率的偏差不超过+/-100 PPM。因此，DUT必须能够以+/-100 PPM的速率接受帧，以符合标准。
Very few clock circuits are precisely +/- 0.0 PPM because:
极少数时钟电路精确为+/-0.0 PPM，因为：
1. The Ethernet standards allow a maximum variance of +/- 100 PPM over time. Therefore, it is normal for the frequency of the oscillator circuits to experience variation over time and over a wide temperature range, among other external factors.
1. 以太网标准允许随时间变化的最大偏差为+/-100 PPM。因此，除了其他外部因素外，振荡器电路的频率随时间和较宽的温度范围发生变化是正常的。
2. The crystals, or clock modules, usually have a specific +/- PPM variance that is significantly better than +/- 100 PPM. Oftentimes, this is +/- 30 PPM or better in order to be considered a "certification instrument".
2. 晶体或时钟模块通常具有特定的+/-PPM方差，显著优于+/-100 PPM。通常，这是+/-30 PPM或更好，以便被视为“认证仪器”。
When testing an Ethernet switch throughput at "line rate", any specific switch will have a clock-rate variance. If a test set is running +1 PPM faster than a switch under test and a sustained line-rate test is performed, a gradual increase in latency and, eventually, packet drops as buffers fill and overflow in the switch, can be observed. Depending on how much clock variance there is between the two connected systems, the effect may be seen after the traffic stream has been running for a few hundred microseconds, a few milliseconds, or seconds. The same low latency, and no packet loss, can be demonstrated by setting the test set's link occupancy to slightly less than 100 percent link occupancy. Typically, 99 percent link occupancy produces excellent low latency and no packet loss. No Ethernet switch or router will have a transmit clock rate of exactly +/- 0.0 PPM. Very few (if any) test sets have a clock rate that is precisely +/- 0.0 PPM.
当以“线路速率”测试以太网交换机吞吐量时，任何特定交换机都会有时钟速率差异。如果测试集的运行速度比正在测试的交换机快+1 PPM，并且执行了持续的线路速率测试，则可以观察到延迟逐渐增加，并最终随着交换机中缓冲区的填充和溢出而导致数据包丢失。根据两个连接的系统之间的时钟差异大小，在流量流运行几百微秒、几毫秒或几秒钟后，可能会看到影响。通过将测试集的链路占用率设置为略低于100%的链路占用率，可以证明相同的低延迟和无数据包丢失。通常，99%的链路占用率产生出色的低延迟和无数据包丢失。任何以太网交换机或路由器的传输时钟速率都不会精确为+/-0.0 PPM。很少（如果有）测试集的时钟频率精确为+/-0.0 PPM。
Test-set equipment manufacturers are well aware of the standards and allow a software-controlled +/- 100 PPM "offset" (clock-rate adjustment) to compensate for normal variations in the clock speed of DUTs. This offset adjustment allows engineers to determine the approximate speed at which the connected device is operating and verify that it is within parameters allowed by standards.
测试设备制造商充分了解这些标准，并允许软件控制+/-100 PPM“偏移”（时钟频率调整），以补偿DUT时钟速度的正常变化。此偏移调整允许工程师确定连接设备运行的近似速度，并验证其是否在标准允许的参数范围内。
"Line rate" can be measured in terms of "frame rate":
“行速率”可以用“帧速率”来衡量：
Frame Rate = Transmit-Clock-Frequency /
(Frame-Length*8 + Minimum_Gap + Preamble + Start-Frame Delimiter)
Frame Rate = Transmit-Clock-Frequency /
(Frame-Length*8 + Minimum_Gap + Preamble + Start-Frame Delimiter)
Minimum_Gap represents the interframe gap. This formula "scales up" or "scales down" to represent 1 GB Ethernet, 10 GB Ethernet, and so on.
最小_间隙表示帧间间隙。此公式“向上扩展”或“向下扩展”表示1GB以太网、10GB以太网等。
Example for 1 GB Ethernet speed with 64-byte frames:
具有64字节帧的1 GB以太网速度示例：
Frame Rate = 1,000,000,000 / (64*8 + 96 + 56 + 8)
Frame Rate = 1,000,000,000 / (64*8 + 96 + 56 + 8)
= 1,000,000,000 / 672
= 1,000,000,000 / 672
= 1,488,095.2 FPS
=1488095.2 FPS
Considering the allowance of +/- 100 PPM, a switch may "legally" transmit traffic at a frame rate between 1,487,946.4 FPS and 1,488,244 FPS. Each 1 PPM variation in clock rate will translate to a frame-rate increase or decrease of 1.488 FPS.
考虑到+/-100 PPM的余量，交换机可以以1487946.4 FPS和1488244 FPS之间的帧速率“合法”传输业务。时钟速率的每1 PPM变化将转化为帧速率增加或减少1.488 FPS。
In a production network, it is very unlikely that one would see precise line rate over a very brief period. There is no observable difference between dropping packets at 99% of line rate and 100% of line rate.
在生产网络中，很难在很短的时间内看到精确的生产线速度。在99%线路速率和100%线路速率下丢弃数据包之间没有明显差异。
Line rate can be measured at 100% of line rate with a -100 PPM adjustment.
测线率可在100%测线率下测量，并进行-100 PPM调整。
Line rate SHOULD be measured at 99.98% with a 0 PPM adjustment.
测线率应为99.98%，并进行0 PPM调整。
The PPM adjustment SHOULD only be used for a line-rate measurement.
PPM调整应仅用于线路速率测量。
Buffer Size: The term "buffer size" represents the total amount of frame-buffering memory available on a DUT. This size is expressed in B (bytes), KB (kilobytes), MB (megabytes), or GB (gigabytes). When the buffer size is expressed, an indication of the frame MTU (Maximum Transmission Unit) used for that measurement is also necessary, as well as the CoS (Class of Service) or DSCP (Differentiated Services Code Point) value set, as oftentimes the buffers are carved by a quality-of-service implementation. Please refer to Section 3 of [RFC8239] for further details.
缓冲区大小：术语“缓冲区大小”表示DUT上可用的帧缓冲内存总量。此大小以B（字节）、KB（千字节）、MB（兆字节）或GB（千兆字节）表示。当表示缓冲器大小时，还需要指示用于该测量的帧MTU（最大传输单元）以及CoS（服务类别）或DSCP（区分服务代码点）值集，因为缓冲器通常由服务质量实现来划分。请参考[RFC8239]第3节了解更多详细信息。
Example: The Buffer Size of the DUT when sending 1518-byte frames is 18 MB.
示例：发送1518字节帧时，DUT的缓冲区大小为18MB。
Port Buffer Size: The port buffer size is the amount of buffer for a single ingress port, a single egress port, or a combination of ingress and egress buffering locations for a single port. We mention the three locations for the port buffer because the DUT's
端口缓冲区大小：端口缓冲区大小是单个入口端口、单个出口端口或单个端口的入口和出口缓冲位置组合的缓冲量。我们提到端口缓冲区的三个位置，因为DUT
buffering scheme can be unknown or untested, so knowing the buffer location helps clarify the buffer architecture and, consequently, the total buffer size. The Port Buffer Size is an informational value that MAY be provided by the DUT vendor. It is not a value that is tested by benchmarking. Benchmarking will be done using the Maximum Port Buffer Size or Maximum Buffer Size methodology.
缓冲方案可能未知或未经测试，因此了解缓冲区位置有助于澄清缓冲区体系结构，从而确定缓冲区的总大小。端口缓冲区大小是DUT供应商可能提供的信息值。这不是一个通过基准测试的值。将使用最大端口缓冲区大小或最大缓冲区大小方法进行基准测试。
Maximum Port Buffer Size: In most cases, this is the same as the Port Buffer Size. In a certain type of switch architecture called "SoC" (switch on chip), there is a port buffer and a shared buffer pool available for all ports. The Maximum Port Buffer Size, in terms of an SoC buffer, represents the sum of the port buffer and the maximum value of shared buffer allowed for this port, defined in terms of B (bytes), KB (kilobytes), MB (megabytes), or GB (gigabytes). The Maximum Port Buffer Size needs to be expressed along with the frame MTU used for the measurement and the CoS or DSCP bit value set for the test.
最大端口缓冲区大小：在大多数情况下，这与端口缓冲区大小相同。在一种称为“SoC”（片上交换机）的交换机体系结构中，有一个端口缓冲区和一个可用于所有端口的共享缓冲池。以SoC缓冲区表示的最大端口缓冲区大小表示端口缓冲区和该端口允许的最大共享缓冲区值之和，以B（字节）、KB（千字节）、MB（兆字节）或GB（千兆字节）定义。最大端口缓冲区大小需要与用于测量的帧MTU以及为测试设置的CoS或DSCP位值一起表示。
Example: A DUT has been measured to have 3 KB of port buffer for 1518-byte frames, and a total of 4.7 MB of maximum port buffer for 1518-byte frames and a CoS of 0.
示例：经测量，DUT的1518字节帧具有3KB的端口缓冲区，1518字节帧的最大端口缓冲区总计为4.7MB，CoS为0。
Maximum DUT Buffer Size: This is the total buffer size that a DUT can be measured to have. It is most likely different than the Maximum Port Buffer Size. It can also be different from the sum of Maximum Port Buffer Size. The Maximum Buffer Size needs to be expressed along with the frame MTU used for the measurement and along with the CoS or DSCP value set during the test.
最大DUT缓冲区大小：这是可以测量DUT的总缓冲区大小。它很可能与最大端口缓冲区大小不同。它也可以不同于最大端口缓冲区大小之和。最大缓冲区大小需要与用于测量的帧MTU以及测试期间设置的CoS或DSCP值一起表示。
Example: A DUT has been measured to have 3 KB of port buffer for 1518-byte frames and a total of 4.7 MB of maximum port buffer for 1518-byte frames. The DUT has a Maximum Buffer Size of 18 MB at 1500 B and a CoS of 0.
示例：经测量，一个DUT的1518字节帧的端口缓冲区为3KB，1518字节帧的最大端口缓冲区总计为4.7MB。DUT在1500 B时的最大缓冲区大小为18 MB，CoS为0。
Burst: A burst is a fixed number of packets sent over a percentage of line rate for a defined port speed. The amount of frames sent is evenly distributed across the interval T. A constant, C, can be defined to provide the average time between two evenly spaced consecutive packets.
突发：突发是一个固定数量的数据包，在一定的端口速度下以一定的线速率发送。发送的帧量均匀分布在间隔T上。可以定义常数C，以提供两个均匀间隔的连续数据包之间的平均时间。
Microburst: A microburst is a type of burst where packet drops occur when there is not sustained or noticeable congestion on a link or device. One characteristic of a microburst is when the burst is not evenly distributed over T and is less than the constant C (C = the average time between two evenly spaced consecutive packets).
微突发：微突发是一种突发类型，当链路或设备上没有持续或明显的拥塞时，会发生丢包。微爆发的一个特征是当爆发不是均匀分布在T上并且小于常数C（C=两个均匀间隔的连续数据包之间的平均时间）时。
Intensity of Microburst: This is a percentage and represents the level, between 1 and 100%, of the microburst. The higher the number, the higher the microburst is.
微爆发强度：这是一个百分比，代表微爆发的水平，介于1%和100%之间。数值越高，微爆发越高。
I=[1-[ (Tp2-Tp1)+(Tp3-Tp2)+....(TpN-Tp(n-1) ] / Sum(packets)]]*100
I=[1-[ (Tp2-Tp1)+(Tp3-Tp2)+....(TpN-Tp(n-1) ] / Sum(packets)]]*100
The above definitions are not meant to comment on the ideal sizing of a buffer but rather on how to measure it. A larger buffer is not necessarily better and can cause issues with bufferbloat.
上面的定义并不是要评论缓冲区的理想大小，而是要评论如何度量缓冲区。较大的缓冲区并不一定更好，可能会导致缓冲区膨胀问题。
When measuring buffering on a DUT, it is important to understand the behavior of each and every port. This provides data for the total amount of buffering available on the switch. The terms of buffer efficiency help one understand the optimum packet size for the buffer or the real volume of the buffer available for a specific packet size. This section does not discuss how to conduct the test methodology; instead, it explains the buffer definitions and what metrics should be provided for comprehensive data center device-buffering benchmarking.
在测量DUT上的缓冲时，了解每个端口的行为非常重要。这将提供交换机上可用缓冲总量的数据。缓冲区效率的术语有助于了解缓冲区的最佳数据包大小或特定数据包大小的实际可用缓冲区容量。本节不讨论如何进行测试方法；相反，它解释了缓冲区定义，以及应该为全面的数据中心设备缓冲基准测试提供哪些指标。
When the DUT buffer is measured:
测量DUT缓冲器时：
- The buffer size MUST be measured.
- 必须测量缓冲区大小。
- The port buffer size MAY be provided for each port.
- 可以为每个端口提供端口缓冲区大小。
- The maximum port buffer size MUST be measured.
- 必须测量最大端口缓冲区大小。
- The maximum DUT buffer size MUST be measured.
- 必须测量最大DUT缓冲区大小。
- The intensity of the microburst MAY be mentioned when a microburst test is performed.
- 在进行微冲击波试验时，可提及微冲击波的强度。
- The CoS or DSCP value set during the test SHOULD be provided.
- 应提供测试期间设置的CoS或DSCP值。
The term "Incast", very commonly utilized in the data center, refers to the many-to-one or many-to-many traffic patterns. As defined in this section, it measures the number of ingress and egress ports and the percentage of synchronization attributed to them. Typically, in the data center, it would refer to many different ingress server ports (many), sending traffic to a common uplink (many-to-one), or multiple uplinks (many-to-many). This pattern is generalized for any network as many incoming ports sending traffic to one or a few uplinks.
术语“Incast”在数据中心中非常常用，指的是多对一或多对多的流量模式。如本节所定义，它测量入口和出口端口的数量以及归因于它们的同步百分比。通常，在数据中心中，它指的是多个不同的入口服务器端口（多个），将流量发送到公共上行链路（多对一）或多个上行链路（多对多）。此模式适用于任何网络，只要有多个传入端口将流量发送到一个或几个上行链路。
Synchronous arrival time: When two or more frames of sizes L1 and L2 arrive at their respective ingress port or multiple ingress ports and there is an overlap of arrival times for any of the bits on the DUT, then the L1 and L2 frames have synchronous arrival times. This is called "Incast", regardless of whether the pattern is many-to-one (simpler) or many-to-many.
同步到达时间：当大小为L1和L2的两个或多个帧到达其各自的入口端口或多个入口端口，并且DUT上的任何位的到达时间重叠时，则L1和L2帧具有同步到达时间。无论模式是多对一（更简单）还是多对多，这都称为“Incast”。
Asynchronous arrival time: This is any condition not defined by "synchronous arrival time".
异步到达时间：这是“同步到达时间”未定义的任何条件。
Percentage of synchronization: This defines the level of overlap (amount of bits) between frames of sizes L1,L2..Ln.
同步百分比：这定义了大小为L1、L2..Ln的帧之间的重叠级别（位数）。
Example: Two 64-byte frames of length L1 and L2 arrive at ingress port 1 and port 2 of the DUT. There is an overlap of 6.4 bytes between the two, where the L1 and L2 frames were on their respective ingress ports at the same time. Therefore, the percentage of synchronization is 10%.
示例：长度为L1和L2的两个64字节帧到达DUT的入口端口1和端口2。两者之间有6.4字节的重叠，其中L1和L2帧同时位于各自的入口端口上。因此，同步的百分比为10%。
Stateful traffic: Stateful traffic is packets exchanged with a stateful protocol, such as TCP.
有状态流量：有状态流量是使用有状态协议（如TCP）交换的数据包。
Stateless traffic: Stateless traffic is packets exchanged with a stateless protocol, such as UDP.
无状态流量：无状态流量是使用无状态协议（如UDP）交换的数据包。
In this scenario, buffers are used on the DUT. In an ingress buffering mechanism, the ingress port buffers would be used along with virtual output queues, when available, whereas in an egress buffering mechanism, the egress buffer of the one outgoing port would be used.
在这种情况下，在DUT上使用缓冲区。在入口缓冲机制中，入口端口缓冲区将在可用时与虚拟输出队列一起使用，而在出口缓冲机制中，将使用一个输出端口的出口缓冲区。
In either case, regardless of where the buffer memory is located in the switch architecture, the Incast creates buffer utilization.
在这两种情况下，无论缓冲存储器位于交换机体系结构中的何处，Incast都会创建缓冲利用率。
When one or more frames have synchronous arrival times at the DUT, they are considered to be forming an Incast.
当一个或多个帧在DUT处具有同步到达时间时，它们被认为正在形成Incast。
It is a MUST to measure the number of ingress and egress ports.
必须测量进出口的数量。
It is a MUST to have a non-null percentage of synchronization, which MUST be specified.
必须具有非空的同步百分比，必须指定该百分比。
In data center networking, a balanced network is a function of maximal throughput and minimal loss at any given time. This is captured by the Goodput [TCP-INCAST]. Goodput is the application-level throughput. For standard TCP applications, a very small loss can have a dramatic effect on application throughput. [RFC2647] provides a definition of Goodput; the definition in this document is a variant of that definition.
在数据中心网络中，平衡网络是在任何给定时间实现最大吞吐量和最小损失的函数。这由Goodput[TCP-INCAST]捕获。Goodput是应用程序级别的吞吐量。对于标准TCP应用程序，非常小的损失可能会对应用程序吞吐量产生显著影响。[RFC2647]提供了Goodput的定义；本文件中的定义是该定义的变体。
Goodput is the number of bits per unit of time forwarded to the correct destination interface of the DUT, minus any bits retransmitted.
Goodput是转发到DUT的正确目标接口的每单位时间的位数，减去任何重新传输的位数。
In data center benchmarking, the goodput is a value that SHOULD be measured. It provides a realistic idea of the usage of the available bandwidth. A goal in data center environments is to maximize the goodput while minimizing loss.
在数据中心基准测试中，goodput是一个应该测量的值。它提供了可用带宽使用的现实想法。数据中心环境中的一个目标是在最大限度地减少损失的同时最大限度地提高收益。
The Goodput, G, is then measured by the following formula:
然后，通过以下公式测量Goodput，G：
G = (S/F) x V bytes per second
G = (S/F) x V bytes per second
- S represents the payload bytes, not including packet or TCP headers.
- S表示有效负载字节，不包括数据包或TCP头。
- F is the frame size.
- F是帧大小。
- V is the speed of the media in bytes per second.
- V是媒体的速度，以字节/秒为单位。
Example: A TCP file transfer over HTTP on 10 GB/s media.
示例：在10 GB/s介质上通过HTTP进行TCP文件传输。
The file cannot be transferred over Ethernet as a single continuous stream. It must be broken down into individual frames of 1500 B when the standard MTU is used. Each packet requires 20 B of IP header information and 20 B of TCP header information; therefore, 1460 B are available per packet for the file transfer. Linux-based systems are further limited to 1448 B, as they also carry a 12 B timestamp. Finally, in this example the date is transmitted over Ethernet, which adds 26 B of overhead per packet to 1500 B, increasing it to 1526 B.
文件不能作为单个连续流通过以太网传输。当使用标准MTU时，必须将其分解为1500 B的单个框架。每个数据包需要20B的IP报头信息和20B的TCP报头信息；因此，对于文件传输，每个数据包都有1460b可用。基于Linux的系统进一步限制为1448B，因为它们还带有12B的时间戳。最后，在本例中，数据通过以太网传输，这将每个数据包的开销增加到26 B，达到1500 B，增加到1526 B。
G = 1460/1526 x 10 Gbit/s, which is 9.567 Gbit/s or 1.196 GB/s.
G=1460/1526 x 10 Gbit/s，即9.567 Gbit/s或1.196 GB/s。
Please note: This example does not take into consideration the additional Ethernet overhead, such as the interframe gap (a minimum of 96 bit times), nor does it account for collisions (which have a variable impact, depending on the network load).
请注意：此示例未考虑额外的以太网开销，例如帧间间隙（至少96位时间），也未考虑冲突（其影响因网络负载而异）。
When conducting Goodput measurements, please document, in addition to the items listed in Section 4.1, the following information:
进行Goodput测量时，除第4.1节中列出的项目外，请记录以下信息：
- The TCP stack used.
- 使用的TCP堆栈。
- OS versions.
- 操作系统版本。
- Network Interface Card (NIC) firmware version and model.
- 网络接口卡（NIC）固件版本和型号。
For example, Windows TCP stacks and different Linux versions can influence TCP-based test results.
例如，Windows TCP堆栈和不同的Linux版本可能会影响基于TCP的测试结果。
Benchmarking activities as described in this memo are limited to technology characterization using controlled stimuli in a laboratory environment, with dedicated address space and the constraints specified in the sections above.
本备忘录中所述的基准测试活动仅限于在实验室环境中使用受控刺激进行技术表征，具有专用地址空间和上述章节中规定的约束条件。
The benchmarking network topology will be an independent test setup and MUST NOT be connected to devices that may forward the test traffic into a production network or misroute traffic to the test management network.
基准网络拓扑将是一个独立的测试设置，不得连接到可能将测试流量转发到生产网络或将流量错误路由到测试管理网络的设备。
Further, benchmarking is performed on a "black-box" basis, relying solely on measurements observable external to the DUT.
此外，基准测试是在“黑盒”的基础上进行的，仅依赖于DUT外部可观察到的测量。
Special capabilities SHOULD NOT exist in the DUT specifically for benchmarking purposes. Any implications for network security arising from the DUT SHOULD be identical in the lab and in production networks.
DUT中不应存在专门用于基准测试的特殊能力。在实验室和生产网络中，DUT对网络安全的影响应相同。
This document does not require any IANA actions.
本文件不要求IANA采取任何行动。
[RFC1242] Bradner, S., "Benchmarking Terminology for Network Interconnection Devices", RFC 1242, DOI 10.17487/RFC1242, July 1991, <https://www.rfc-editor.org/info/rfc1242>.
[RFC1242]Bradner，S.，“网络互连设备的基准术语”，RFC 1242，DOI 10.17487/RFC1242，1991年7月<https://www.rfc-editor.org/info/rfc1242>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，DOI 10.17487/RFC2119，1997年3月<https://www.rfc-editor.org/info/rfc2119>.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for Network Interconnect Devices", RFC 2544, DOI 10.17487/RFC2544, March 1999, <https://www.rfc-editor.org/info/rfc2544>.
[RFC2544]Bradner，S.和J.McQuaid，“网络互连设备的基准测试方法”，RFC 2544，DOI 10.17487/RFC2544，1999年3月<https://www.rfc-editor.org/info/rfc2544>.
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", RFC 5481, DOI 10.17487/RFC5481, March 2009, <https://www.rfc-editor.org/info/rfc5481>.
[RFC5481]Morton，A.和B.Claise，“数据包延迟变化适用性声明”，RFC 5481，DOI 10.17487/RFC5481，2009年3月<https://www.rfc-editor.org/info/rfc5481>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8174]Leiba，B.，“RFC 2119关键词中大写与小写的歧义”，BCP 14，RFC 8174，DOI 10.17487/RFC8174，2017年5月<https://www.rfc-editor.org/info/rfc8174>.
[RFC8239] Avramov, L. and J. Rapp, "Data Center Benchmarking Methodology", RFC 8239, DOI 10.17487/RFC8239, August 2017, <https://www.rfc-editor.org/info/rfc8239>.
[RFC8239]Avramov，L.和J.Rapp，“数据中心基准测试方法”，RFC 8239，DOI 10.17487/RFC8239，2017年8月<https://www.rfc-editor.org/info/rfc8239>.
[RFC2432] Dubray, K., "Terminology for IP Multicast Benchmarking", RFC 2432, DOI 10.17487/RFC2432, October 1998, <https://www.rfc-editor.org/info/rfc2432>.
[RFC2432]Dubrey，K.，“IP多播基准测试术语”，RFC 2432，DOI 10.17487/RFC2432，1998年10月<https://www.rfc-editor.org/info/rfc2432>.
[RFC2647] Newman, D., "Benchmarking Terminology for Firewall Performance", RFC 2647, DOI 10.17487/RFC2647, August 1999, <https://www.rfc-editor.org/info/rfc2647>.
[RFC2647]Newman，D.，“防火墙性能的基准术语”，RFC 2647，DOI 10.17487/RFC2647，1999年8月<https://www.rfc-editor.org/info/rfc2647>.
[RFC2889] Mandeville, R. and J. Perser, "Benchmarking Methodology for LAN Switching Devices", RFC 2889, DOI 10.17487/RFC2889, August 2000, <https://www.rfc-editor.org/info/rfc2889>.
[RFC2889]Mandeville，R.和J.Perser，“局域网交换设备的基准测试方法”，RFC 2889，DOI 10.17487/RFC2889，2000年8月<https://www.rfc-editor.org/info/rfc2889>.
[RFC3918] Stopp, D. and B. Hickman, "Methodology for IP Multicast Benchmarking", RFC 3918, DOI 10.17487/RFC3918, October 2004, <https://www.rfc-editor.org/info/rfc3918>.
[RFC3918]Stopp，D.和B.Hickman，“IP多播基准测试方法”，RFC 3918，DOI 10.17487/RFC3918，2004年10月<https://www.rfc-editor.org/info/rfc3918>.
[TCP-INCAST] Chen, Y., Griffith, R., Zats, D., Joseph, A., and R. Katz, "Understanding TCP Incast and Its Implications for Big Data Workloads", April 2012, <http://yanpeichen.com/ professional/usenixLoginIncastReady.pdf>.
[TCP-INCAST]Chen，Y.，Griffith，R.，Zats，D.，Joseph，A.，和R.Katz，“理解TCP-INCAST及其对大数据工作负载的影响”，2012年4月<http://yanpeichen.com/ professional/UseNixLoginCastReady.pdf>。
Acknowledgments
致谢
The authors would like to thank Al Morton, Scott Bradner, Ian Cox, and Tim Stevenson for their reviews and feedback.
作者要感谢Al Morton、Scott Bradner、Ian Cox和Tim Stevenson的评论和反馈。
Authors' Addresses
作者地址
Lucien Avramov Google 1600 Amphitheatre Parkway Mountain View, CA 94043 United States of America
Lucien Avramov谷歌1600圆形剧场公园路山景，加利福尼亚州94043美利坚合众国
Email: lucien.avramov@gmail.com
Email: lucien.avramov@gmail.com
Jacob Rapp VMware 3401 Hillview Ave. Palo Alto, CA 94304 United States of America
美国加利福尼亚州帕洛阿尔托市Hillview大道3401号，邮编94304
Email: jhrapp@gmail.com
Email: jhrapp@gmail.com